The letter would state the following.
wrote: To whom it may concern:
I, Zaed Nahalis, wish to make a deal with you. I want a contract with the Harmonium, in regards to Arms and Armor. Some of you may have done business with me in the past, and I can assure you that I know and perform my craft exceedingly well, especially when dealing with rarer materials. If you so wish, we can draw up a contract dealing with this, and I can perhaps give your faction a discount on purchases. Not a huge one of course, I still have to keep my business afloat. If you want to reach me in regards to this, please deliver a letter to my dropbox at the Foul Olde Spirit Inn.